Induction of spermatogenesis in isolated hypogonadotropic hypogonadism with exogenous human chorionic gonadotropin.

A 21-year old male patient with isolated hypogonadotropic hypogonadism (IGD) is described. Basal serum levels of testosterone (0.5 ng/ml), FSH (2.1 mIU/ml) and LH (2.3 mIU/ml) were low and did not respond to administration of clomiphene citrate. The FSH and LH responses to LHRH were normal. Pituitary-thyroid and pituitary-adrenal function as well as GH reserve were also normal. However, prolactin (PRL) response to both TRH and metoclopramide were blunted compared with normal male subjects. The patient was treated with human chorionic gonadotropin (HCG). Within 20 months he developed full testicular maturation with spermatogenesis and full androgenization. Serum testosterone levels rose to 6.5-13.5 ng/ml. Both basal serum PRL levels and the response to TRH and metoclopramide became normal. Spermatogenesis and androgenization proceeded in the absence of FSH. These results suggest further trials of treatment with HCG alone in patients with IGD are warranted.